1. Field of the Invention
This invention relates generally to surgery and, more particularly, to electrode systems for use with physiological stimulators.
2. Description of the Related Art
A number of people suffer from arrhythmias each year, such as ventricular fibrillation (VF) and atrial fibrillation (AF), and are often referred to as cardiac patients. It is known that the chances of survival increase if the time between the onset of the arrhythmia and medical treatment is decreased. For example, a cardiac patient's chances of survival decrease about 10% for every minute that elapses after VF begins and before medical treatment, such as defibrillation, is initiated. Since most cardiac patients are away from a hospital at the onset of VF, physiological stimulators, such as automatic external defibrillators (AEDs), pacers, and other medical equipment, have been developed which can be brought to the patient.
An AED defibrillates a patient's heart by providing a defibrillation signal through an electrode system coupled between the patient and AED. The patient's heart is defibrillated in response to the defibrillation signal. The electrode system generally includes an electrode set having a conductive line extending between a connector at one end and an electrode pad at its other end. The electrode set generally includes two conductive lines connected to separate electrode pads and the same connector. The connector and electrode pads couple the conductive lines to the AED and patient, respectively, so that the defibrillation signal flows between them through the conductive lines. Most electrode pads of these types are self-adhesive and disposable.
There are two well accepted placements for these electrode pads. In a first instance, the two electrode pads are placed on the anterior or front portion of the patient's chest in an anterior-anterior placement. In the first instance, one of the pads is placed near the lower left of the patient's thorax near the heart's apex (anterior-apex position) and the other one is positioned on the upper right thorax to the right of the patient's sternum (anterior-sternum position). In a second instance, a first electrode pad is positioned at the anterior-apex position and the second electrode pad is positioned on the posterior or back of the patient (posterior position). In the second instance, the positioning of the electrode pads is typically called an anterior-posterior placement.
There are several problems not addressed by current AEDs and their electrode systems. One problem is that a first responder to a cardiac patient is generally a layperson who provides Basic Life Support (BLS), which includes defibrillation. The first responder preferably uses the anterior-anterior placement for the electrode pads since it is simpler and the first responder is typically not very medically trained. However, when emergency paramedics arrive as second responders, they may prefer to use the anterior-posterior placement because defibrillation and pacing are more effective.
As a result, the electrode system of the first responder is often removed and replaced with that of the second responder in the anterior-posterior placement. If the electrode system of the first responder is not removed, then that of the second responder can be coupled to the patient next to the electrode system of the first responder. This is not desired since the placement of the electrode pads significantly affects the effectiveness of the defibrillation and/or pacing and the health of the patient can be negatively impacted if the correct position is not used.
Further, emergency paramedics generally apply Advanced Life Support (ALS) protocols as recommended by the American Heart Association (AHA). ALS procedures typically include providing various combinations of external pacing, defibrillation, and/or monitoring. Hence, when more advanced medical equipment arrives at the scene, a greater number of different connectors and electrode pads are introduced into the situation.
One type of electrode pads is called QUIK COMBO pads provided by Medtronic, Inc. These electrode pads are useful for monitoring, defibrillation, and pacing. However, when demand pacing is implemented, the monitoring signal is corrupted and separate monitoring electrode pads must be applied to the patient. The monitoring electrode pads are used for electrocardiogram (ECG) monitoring. This is because the QUIK COMBO electrode pads are not effective for monitoring when the patient is being demand paced.
These problems are compounded because some defibrillator manufacturers have designed their electrode systems so that they have connectors that are compatible only with their type of medical equipment and are not compatible with the medical equipment made by other manufacturers. Because of this, if the electrode system of the first responder is not compatible with the AED of the second responder, it is removed from the patient and replaced with an electrode system of the second responder that is compatible.
This is undesirable for several reasons, with one being that it wastes time. Another reason is that more electrode systems are used and the costs increase because they are typically used once and discarded. Multiple pad changes can also cause the skin of the patient to become irritated. Further, in certain situations, it is undesirable to remove a first set of electrode pads already coupled to the patient.
For example, when the patient's heart is being paced in response to a pacing signal flowing through the first set of electrode pads, it is sometimes undesirable to stop pacing. The pacing will be stopped if the first set of electrode pads is removed. In one situation, they are removed so that they can be replaced with a second set of electrode pads. The pacing can be restarted using the second set of electrode pads after they are coupled to the patient, but if it is not done in time, then the health of the patient can be negatively impacted so that his or her chances of survival decrease. Restarting the pacing is sometimes referred to in the art as pacing recapture.
As a result, the incompatibilities in electrode systems made by different manufacturers and the resulting delays in removing and replacing them undesirably interferes with the medical treatment of the patient. Accordingly, what is needed is an electrode system that is compatible with the medical equipment of the different manufacturers. What is also needed is an electrode system that can be changed between different configurations and placements without negatively impacting the health of the patient. There is also a need for a method of providing non-invasive demand pacing that reduces costs, the number of pads used, and the time needed to apply the electrode pads. Further, there is a need for an efficacious method which eliminates corruption of the ECG heart monitoring signal during demand pacing.